book_theme <- list(
  theme_classic(base_size = 13),
  theme(
    plot.margin = margin(0,0,0,0),
    panel.grid = element_blank(),
    strip.background = element_blank(),
    strip.text = element_text(size = 12),
    plot.caption.position = "plot",
    plot.caption = element_text(hjust = 0)
  )
)